It's something that runs through our minds all the time when faced with delicious desserts and junk foods: "I'll just make up for it later at the gym."
Sometimes that gym promise happens,
other most times we conveniently forget about it and carry on with our day.
Unfortunately, we can't 'make up' for overeating or indulging in treats and junk food. Such a bummer.
"Some people give themselves permission to indulge in junk food just because they plan to have a good workout later in the day. It's a common excuse," dietitian Robbie Clark told HuffPost Australia.
"Many people believe that because they exercise, they're in the clear regarding their calorie intake versus their output from exercise. But in reality, many people have no idea how many calories they consume on an average day, and when asked to guess they usually underestimate it."
The impact exercise can have on weight loss is limited if changes are not made to a bad diet.
At the same time, we also tend to overestimate the number of calories we burn through exercise. Yes, those gym machines lie.
"Truth be told, 30 minutes of the best boot camp may not cancel out that burger and fries you had for lunch," Clark said.
"Many people who are wanting to lose weight make the mistake of focusing on exercise, but there is a plethora of research that shows that exercise alone is not enough, and that reducing calorie intake should be the focus for weight loss."
That's not to say exercise isn't important, however.
"While physical activity reduces the risk of a range of health conditions such as heart disease, dementia, some cancers and Type 2 Diabetes, as well as reducing symptoms of depression and anxiety, the impact exercise can have on weight loss is limited if changes are not made to a bad diet. It's rare to lose weight on an exercise-only program."
To understand this better, let's look at the maths.
"Your average moderate intensity workout will burn approximately 300-400 calories in about an hour. That's an hour of hard work with plenty of sweat and heavy breathing," Clark explained.
"Now, if you decide to eat a slice of chocolate cake with the intention of 'working it off later', in the three minutes it will take you to put away the cake, you've consumed around 500 calories. Not even that hard workout you plan to do will burn off the cake you just ate. Plus, you've provided your body with a couple of hundred extra calories to potentially store as fat."
The bottom line is you simply "can't outrun a bad diet".
"If you try to battle a bad diet with exercise, the exercise will lose every time. The best way for successful and sustainable weight loss is to eat a healthy diet in support of -- not a substitute for -- a good exercise program.
Another important, often forgotten, issue is that a calorie is not a calorie, making calorie counting not the ideal method to lose or maintain weight.
"Not all calories are created equal. This is a very common misconception -- that a calorie from fruit is the same as a calorie in chocolate," Clark told HuffPost Australia.
"The calories on paper are not necessarily the calories we actually receive due to the human body being a highly complex biochemical system with elaborate processes that regulate energy balance."
As neuro-endocrinologist Robert Lustig explained in a HuffPost blog: "A calorie is a measurement of energy (a matter of physics), not a value judgement on where that energy goes (a matter of biochemistry)."
Fat, protein and carbohydrates have a different biological influence on satiety, metabolic rate, brain activity, blood sugar and the way our body stores fat.
"Healthy, nutrient-dense foods will keep hunger at bay, help maintain stable blood glucose levels, reduce cravings, and allow your brain to signal to your stomach that it's full," Clark said.
"Nutrient-poor foods will have the opposite effect, causing hormonal dysfunction, spiking insulin levels, increasing cravings, suppressing satiety signals and encouraging overeating."
Essentially, unhealthy food is unhealthy food, no matter how many calories it has.
With this in mind, here's how many burpees it takes for a person of average height and weight to burn of 13 popular foods.
"Firstly, it's important to note that a person's weight, metabolism, duration and intensity are determining factors for the number of calories they will burn while performing this exercise," Clark said.
"These are the approximate amount of burpees an average person weighing around 70kg would have to do in order to burn off certain foods."
ALSO ON HUFFPOST AUSTRALIA